From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756099AbZEKNml (ORCPT ); Mon, 11 May 2009 09:42:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754882AbZEKNle (ORCPT ); Mon, 11 May 2009 09:41:34 -0400 Received: from mx1.emlix.com ([193.175.82.87]:44492 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753045AbZEKNlc (ORCPT ); Mon, 11 May 2009 09:41:32 -0400 From: Johannes Weiner To: Chris Zankel Cc: linux-kernel@vger.kernel.org, Oskar Schirmer Subject: [patch 4/5] xtensa: implement ccount calibration for s6000 Date: Mon, 11 May 2009 15:43:36 +0200 Message-Id: <1242049417-12564-5-git-send-email-jw@emlix.com> In-Reply-To: <1242049417-12564-1-git-send-email-jw@emlix.com> References: <1242049417-12564-1-git-send-email-jw@emlix.com> Organization: emlix gmbh, Goettingen, Germany Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oskar Schirmer Calculate core frequency from timers at boot time instead of assuming a fixed frequency. This is useful as the true frequency is set up by the boot loader, thus variable. Signed-off-by: Oskar Schirmer --- arch/xtensa/Kconfig | 1 + arch/xtensa/variants/s6000/Makefile | 1 + arch/xtensa/variants/s6000/delay.c | 27 +++++++++++++++++++++++++++ 3 files changed, 29 insertions(+), 0 deletions(-) create mode 100644 arch/xtensa/variants/s6000/delay.c diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index 30d21a9..ebe228d 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -80,6 +80,7 @@ config XTENSA_VARIANT_S6000 bool "s6000 - Stretch software configurable processor" select VARIANT_IRQ_SWITCH select ARCH_REQUIRE_GPIOLIB + select XTENSA_CALIBRATE_CCOUNT endchoice config XTENSA_UNALIGNED_USER diff --git a/arch/xtensa/variants/s6000/Makefile b/arch/xtensa/variants/s6000/Makefile index 03b3975..d83f380 100644 --- a/arch/xtensa/variants/s6000/Makefile +++ b/arch/xtensa/variants/s6000/Makefile @@ -1,3 +1,4 @@ # s6000 Makefile obj-y += irq.o gpio.o +obj-$(CONFIG_XTENSA_CALIBRATE_CCOUNT) += delay.o diff --git a/arch/xtensa/variants/s6000/delay.c b/arch/xtensa/variants/s6000/delay.c new file mode 100644 index 0000000..54b2b57 --- /dev/null +++ b/arch/xtensa/variants/s6000/delay.c @@ -0,0 +1,27 @@ +#include +#include +#include +#include + +#define LOOPS 10 +void platform_calibrate_ccount(void) +{ + u32 uninitialized_var(a); + u32 uninitialized_var(u); + u32 b; + u32 tstamp = S6_REG_GREG1 + S6_GREG1_GLOBAL_TIMER; + int i = LOOPS+1; + do { + u32 t = u; + asm volatile( + "1: l32i %0, %2, 0 ;" + " beq %0, %1, 1b ;" + : "=&a"(u) : "a"(t), "a"(tstamp)); + b = xtensa_get_ccount(); + if (i == LOOPS) + a = b; + } while (--i >= 0); + b -= a; + nsec_per_ccount = (LOOPS * 10000) / b; + ccount_per_jiffy = b * (100000UL / (LOOPS * HZ)); +} -- 1.6.3.rc3